1. Field of the Invention
The present invention involves the cloning and isolation of a hybridoma secreting a monoclonal antibody to a highly conserved epitope on peptides that originate in the seminal vesicles.
2. Prior Art
More than 200 proteins ranging in mass from 10-100 kDa are observed when human seminal plasma is analyzed by high-resolution two-dimensional electrophoresis, Edwards et.al., Proteins of Human Semen. I. Two-Dimensional Mappinq of Human Seminal Fluid, CLIN CHEM, 27(8):1335-40 (U.S.A. 1981). Many of the proteins of higher molecular mass in semen undergo proteolysis during liquefaction. Evidence obtained by massage of the prostate or seminal vesicles indicates that several seminal fluid proteins of low molecular mass in the 10-25 kDa range are of vesicular origin. The accessory sex glands, prostate and seminal vesicles contribute the majority of seminal plasma secretory proteins, with the prostate contributing from 15-30% of the ejaculate volume and the seminal vesicles accounting for 50-80%.
In the field of forensic science, attempts to corroborate an alleged rape by verifying the presence of semen in sexual-assault evidence have traditionally relied on microscopic evidence of sperm cells. Because some men lack spermatozoa in the ejaculate due to azoospermia or vasectomy, and because elution and recovery of sperm cells are often hampered by adherence to material evidence, tests for seminal fluid marker proteins, such as prostatic acid phosphates, prostate-specific antigen (P30), gamma glutamyl transpeptidase (GGT), choline, spermine, and lactate dehydrogenase (LDH) have been reported. Assays of choline, GGT, spermine, and LDH each have significant drawbacks and are not in general use.
In current forensic practice, the test for prostatic acid phosphatase is considered a presumptive, rather than a diagnostic, semen assay by most pathologists and forensic specialists. Acid phosphatase activity from endogenous vaginal sources or from the many plant materials that contain the enzyme may give false positive results. The enzyme also declines in activity upon storage at room temperature. For these reasons, when small amounts of semen may be present, as in eluates of dried semen stains from vaginal swabs or undergarments, the acid phosphatase activity cannot be attributed exclusively to semen.
Prostate-specific antigen (P30), a 32-kDA protein of prostatic origin, has been utilized by the forensic community as a semen marker since its introduction in 1978, Sensabaugh, Isolation and Characterization of a Semen Specific Protein from Human Seminal Plasma: A Potential Marker for Semen Identification, J FORENSIC SCI, 23:106-15 (U.S.A. 1978). Immunoassays based upon polyclonal antisera are generally employed, Graves et. al., Post Coital Detection of a Male-Specific Semen Protein: Application to the Detection of Rape, N ENGL J MED, 132:338-43 (U.S.A. 1985).
Because monoclonal-antibody-based immunoassays offer advantages over polyclonal immunoreagents, including their constant class and isotype, constant affinity, and availability in virtually unlimited supply, there is a need to develop monoclonal antibody probes useful for forensic application in semen identification.